Stress sensor and fabrication method for the same

Abstract

The stress sensor includes: a magnetic material; a stress applied portion on the magnetic material; a magnet disposed so as to be adjacent to by a magnetic material; a magnetic sensor disposed via the magnetic material so as to be opposed to the stress applied portion, wherein the magnetic sensor detects a magnetic flux emitted from a magnetic domain generated in the magnetic material by a local stress applied to the stress applied portion. The local stress or stress distribution can be detected with a convenience structure, and can obtain a high spatial resolution by using a stress response phenomenon of a single magnetic domain.

What is claimed is: 
     
         1 . A stress sensor comprising:
 a magnetic material;   a stress applied portion on the magnetic material;   a magnet disposed so as to be adjacent to the magnetic material; and   a magnetic sensor disposed via the magnetic material so as to be opposed to the stress applied portion, wherein   the magnetic sensor detects a magnetic flux emitted from a magnetic domain generated in the magnetic material by a local stress applied to the stress applied portion.   
     
     
         2 . The stress sensor according to  claim 1 , wherein
 a saturation magnetic field is applied to the magnetic material due to the magnet, and an external magnetic field due to the magnet and a stress-induced anisotropic magnetic field in a reverse direction are applied thereto with the local stress, and then a single magnetic bubble is generated in the magnetic material, and then a magnetic flux emitted from the magnetic bubble is detected by the magnetic sensor, and thereby the local stress can be detected.   
     
     
         3 . A stress sensor comprising:
 a magnetic material;   a stress applied portion of the magnetic material;   a magnet disposed so as to be adjacent to the magnetic material; and   a magnetic sensor disposed via the magnetic material so as to be opposed to the stress applied portion, wherein   a magnetic flux emitted from a magnetic domain is detected by the magnetic sensor, and thereby displacement of a magnetic domain due to stress distribution is detected.   
     
     
         4 . The stress sensor according to  claim 3 , wherein
 a magnetic field for generating magnetic bubble is applied to the magnetic material by the magnet, and a stress-induced anisotropic magnetic field is applied due to the stress distribution, and thereby displacement of the magnetic bubble is generated, and then a magnetic flux emitted from the magnetic bubble is detected by the magnetic sensor, and thereby the stress distribution can be detected.   
     
     
         5 . The stress sensor according to  claim 1 , wherein
 a plurality of the magnetic sensors are disposed thereon.   
     
     
         6 . The stress sensor according to  claim 3 , wherein
 a plurality of the magnetic sensors are disposed thereon.   
     
     
         7 . The stress sensor according to  claim 1 , wherein
 the magnetic sensor is composed of a Hall element, and the Hall element is disposed on the magnetic material so as to be contacted to the magnetic material.   
     
     
         8 . The stress sensor according to  claim 3 , wherein
 the magnetic sensor is composed of a Hall element, and the Hall element is disposed on the magnetic material so as to be contacted to the magnetic material.   
     
     
         9 . The stress sensor according to  claim 7 , wherein
 the material of the Hall element is a bismuth (Bi).   
     
     
         10 . The stress sensor according to  claim 8 , wherein
 the material of the Hall element is a bismuth (Bi).   
     
     
         11 . The stress sensor according to  claim 1  further comprising
 an insulating layer disposed on the magnetic sensor, wherein the magnet is disposed on the insulating layer. 
 
     
     
         12 . The stress sensor according to  claim 3  further comprising
 an insulating layer disposed on the magnetic sensor, wherein the magnet is disposed on the insulating layer. 
 
     
     
         13 . The stress sensor according to  claim 1 , wherein
 the magnet is formed of a magnetic substance thin film.   
     
     
         14 . The stress sensor according to  claim 3 , wherein
 the magnet is formed of a magnetic substance thin film.   
     
     
         15 . The stress sensor according to  claim 1 , wherein
 the magnetic sensor is disposed on one surface of the magnetic material, and the magnet is disposed on another surface of the magnetic material.   
     
     
         16 . The stress sensor according to  claim 1 , wherein
 the magnet and the magnetic sensor are disposed on one surface of the magnetic material.   
     
     
         17 . The stress sensor according to  claim 3 , wherein
 the magnet and the magnetic sensor are disposed on one surface of the magnetic material.   
     
     
         18 . The stress sensor according to  claim 16 , wherein
 the one surface of the magnetic material is a back side surface of the magnetic material.   
     
     
         19 . The stress sensor according to  claim 17 , wherein
 the one surface of the magnetic material is a back side surface of the magnetic material.   
     
     
         20 . The stress sensor according to  claim 16 , wherein
 the one surface of the magnetic material is a front side surface of the magnetic material.   
     
     
         21 . The stress sensor according to  claim 17 , wherein
 the one surface of the magnetic material is a front side surface of the magnetic material.   
     
     
         22 . The stress sensor according to  claim 1 , wherein
 the magnetic sensor is disposed on the magnetic material so as to be contacted to the magnetic material.   
     
     
         23 . The stress sensor according to  claim 3 , wherein
 the magnetic sensor is disposed on the magnetic material so as to be contacted to the magnetic material.   
     
     
         24 . A fabrication method for a stress sensor comprising:
 preparing a magnetic material;   disposing a magnet so as to be adjacent to the magnetic material; and   disposing a magnetic sensor via the magnetic material so as to be opposed to the stress applied portion on the magnetic material, wherein   the magnetic sensor is a magnetic sensor configured to detect a magnetic flux emitted from a magnetic domain generated in the magnetic material due to a local stress applied to the stress applied portion, wherein   a step of fabricating the magnetic sensor comprises:
 forming an insulating layer on the magnetic material; 
 pattern-forming a bismuth electrode layer on the insulating layer; 
 pattern-forming a pad electrode on the bismuth electrode layer; 
 forming a passivation film on the pad electrode; 
 forming an aperture to the pad electrode in the passivation film; and 
 connecting a bonding wire to the aperture. 
   
     
     
         25 . A fabrication method for a stress sensor comprising:
 preparing a magnetic material;   disposing a magnet so as to be adjacent to the magnetic material; and   disposing a magnetic sensor via the magnetic material so as to be opposed to the stress applied portion on the magnetic material, wherein   the magnetic sensor is a magnetic sensor configured to detect displacement of a magnetic domain due to stress distribution by detecting a magnetic flux emitted from the magnetic domain, wherein   a step of fabricating the magnetic sensor comprises: forming an insulating layer on the magnetic material;
 pattern-forming a bismuth electrode layer on the insulating layer; 
 pattern-forming a pad electrode on the bismuth electrode layer; 
 forming a passivation film on the pad electrode; 
 forming an aperture to the pad electrode in the passivation film; and 
   connecting a bonding wire to the aperture.